1. Field of the Invention
This invention relates to a centrifugal pump device, and more particularly to a centrifugal pump device for a heat-dissipating system.
2. Description of the Related Art
Referring to FIG. 1A, a heat-dissipating system includes a centrifugal pump unit 5, and is used for dissipating heat from a central processing unit (CPU) of a computer (not shown) via a CPU water jacket 6. The pump unit 5 forces a liquid, such as water, to circulate along a conduit unit 7 in the heat-dissipating system. The liquid flows through the water jacket 6, the pump unit 5, a tank 8, and a heat-dissipating unit 9 including a plurality of fins. Further referring to FIGS. 1B and 1C, the pump unit 5 may be a first conventional pump device (A) mounted with an internal stator motor 51 or a second conventional pump device (B) mounted with an external stator motor 52. The external stator motor 52 includes an output shaft 53, a rotor 54 connected fixedly to the output shaft 53, a plurality of radially extending stator cores 55 arranged around the rotor 54, and a plurality of stator windings 56 wound respectively on the stator cores 55.
The aforesaid conventional centrifugal pump device including the external stator motor 52 suffers from many disadvantages. For example, to provide a sufficient power output from the external stator motor 52, the total length of the windings 56 must be greater than a threshold value. Thus, the axial length of the stator cores 55 is increased. As a result, the total axial length of the centrifugal pump device is large and therefore goes against the current trend toward miniaturization in notebook computer design.
Referring to FIG. 1D, in another heat-dissipating system, a third conventional centrifugal pump device 5′ includes a housing 57 in thermal contact with a CPU 6′. The third conventional centrifugal pump device 5′, however, also has a long axial length.